1. Field of the Invention
The present Invention relates to a transducer, and in particular to a transducer suitable for use in a hybrid optical and radio communications system.
2. Related Art
Hybrid optical and radio communications systems, and in particular radio-fibre systems are expected to find an increasing role in telecoms networks over the next decade due to their ability to combine the flexible and low cost distribution afforded by optical transmission with `wireless` radio transmission in areas such as personal mobility or antenna remoting.
Demand for broadband services to the home and to small businesses is expected to increase dramatically over the next decade. Optical fibre and millimetre-wave radio are both capable of supporting the large bandwidth requirements associated with these services. Running fibre direct to the home or business is one way of providing high capacity, but for operational reasons this is not always an appropriate solution. Alternatively millimetre-wave radio systems, such as the RACE Mobile Broadband system or radio LANs, are flexible and offer the advantage of expedient provision. It is likely, therefore, that a hybrid network comprising both radio and fibre will play a significant role in early broadband local-access systems.
Such a hybrid optical and radio system is described in Wake, D., Smith, I. C., Walker, N. G., Henning, I. D., and Carver, R. D. `Video transmission over a 40 GHz radio-fibre link`, Electron. Lett. , 28, 1992, pp 2024-2025, and also in Smith, I. C., and Ellis, B. J.: `A wideband mm-wave fibre-fed radio distribution point demonstrator`. ICC'92 Conference Record, 1992, pp. 100-104
Necessarily in these systems while some equipment, particularly the bulky and expensive equipment, may be located in a central benign environment, other equipment, particularly the optical to radio transducer, must be located remotely. The requirements demanded of any remotely sited equipment are severe for example in terms of cost, size, weight, frequency stability and power consumption, and because in any practical system there will be many more remote sites than central sites, progress in meeting the requirements of remotely sited equipment limits the deployment of these systems.